Hydroxy-functional polyesters prepared from epoxidized aliphatic acids are mentioned in U.S. Pat. No. 3,184,439 to Brack and in the article of Swern et al. in the Journal of the American Chemical Society, volume 70, year 1948, page 1228 et seq. However, these polyesters are either of low molecular weight or they are thermosets (i.e. substantially crosslinked), making them unsuitable for a wide variety of applications.
It is an object of the present invention to provide high molecular weight thermoplastic hydroxy-functional polyesters. It is a further object of the present invention to provide high molecular weight thermoplastic hydroxy-functionalized polyesters derived from epoxidized fatty acids.
Traditional polymers, including polyesters, have been derived largely from petroleum. As a source material, petroleum presents costs and problems in the form of pollution, waste disposal, and environmental remediation, much of which have been associated with cracking and refining of this non-renewable resource. Consequently, the modern chemical industries have been seeking to develop “green chemistry” in which less costly and less problematic source, preferably renewable sources, provide a replacement for petroleum in many applications. As part of this effort, it is an industry recognized goal to obtain alternative routes to polymers identical to petroleum-based polymers, and to obtain novel routes to polymers at least functionally equivalent thereto.
The use of epoxidized fatty acids in the polymerization of polyesters according to the present invention thus meets a need in the field of thermoplastic polymers, since epoxidized fatty acids may be obtained directly from renewable sources such as seed oils (e.g., vernolic acid) and/or may be readily prepared from such sources (e.g., by epoxygenation of double bonds in unsaturated fatty acids). Thus, renewable sources of fatty acids and fatty acid esters (e.g., mono-, di-, and tri-acyl glycerols) can thereby provide starting materials for polyesters according to the present invention.